Oil & Fuel How important are 300 hour HST oil changes for Kubota B7510 used as a mower?

[Rod in Forfar]

Coming up to 600 hours on my Kubota B7510 which runs a 5' belly mower and a 4' bush hog. When I changed the oil and filters at 300 hours there was no evidence whatever of anything but pristine oil and clean drain plugs. Have all of those old HST Kubotas really had their oil changed every 300 hours?

The reason I ask is that I never changed the oil in the running gear of my Toyota 4Runner, and it ran well over 400,000 km without a whimper, notwithstanding Toyota's stern requirements for expensive service. My 4WD Tacoma so far is the same. All I have done is grease them faithfully.

I'm willing to do the maintenance if it does any good, but I think I'll skip that long strainer underneath.

 

[Trials]

You live in Ontario, we live in a moist environment, the biggest hazard is water accumulation from condensation if the equipment is stored in sub-zero temps during the winter. If it was stored in a heated garage that's a completely different thing. You can see the presence of water in your HST if it appears milky in colour after you run it for a while. If you were operating the equipment in the winter the problems would be far greater and become apparent as ice crystals would clog the filters and starve the pump for oil. (they make nasty noises when that starts to happen) You might not even notice it in the summer although water getting into places that should only contain oil is not a particularly good thing, it makes things rust. Putting grease into fittings is equally important for the same reason, it not only lubricates moving parts but it also displaces any water that has collected in places that it shouldn't be.

 

[newbury]

Trust but verify.

Pull a sample and send it to a Used Oil Analysis site (I use blackstone).
I was advised here by many "forget the expense, just change the oil" at EVERY 3,000 to 5,000 miles on my F350. I sent off samples every once and a while after I changed to T6, finally changed it at 20,000, might have been able to go another 5,000. Every oil change would have been about $75 for oil and filter.

I run T6 because I don't have a functioning block heater and it starts well cold.

 

[Trials]

Pretty sure he is referring to the hydraulic oil in the hydrostatic transmission and not the engine oil. T6 wouldn't be so good for that.

 

[newbury]

Pretty sure he is referring to the hydraulic oil in the hydrostatic transmission and not the engine oil. T6 wouldn't be so good for that.

I KNOW he's referring to the HST, but the principle of "Trust but verify" remains the same. If he THINKS his oil is good a UOA would confirm. My point was NOT to put T6 in instead of SUDT.

 

[Billrog]

Ran my last HST tractor over 4000 hrs. and maybe changed the trans hydraulic oil 3 times filter 5 or 6. Used the tractor nearly every day summer and winter sold it 2 years ago and it's still going strong. I'm not saying it was good practice just that I think every 300 hrs. is excessive.

 

[newbury]

Ran my last HST tractor over 4000 hrs. and maybe changed the trans hydraulic oil 3 times filter 5 or 6. Used the tractor nearly every day summer and winter sold it 2 years ago and it's still going strong. I'm not saying it was good practice just that I think every 300 hrs. is excessive.

Yup, and if the average TBN'er who puts on 200 hours a year OR LESS ran their tractor for 7 years they might have sold it. 300 hours is a mfg CTA action for warrantied equipment.

If your equipment is OUT of warranty why follow their rules for maintenance when you can check if it is needed?

Some posters here advocate changing the fluids annually. That may be fine for their usage but not for my wallet. A UOA is relatively cheap compared to a complete HST fluid change.

 

[Trials]

... Have all of those old HST Kubotas really had their oil changed every 300 hours? ...

The tractors stored in the cold and used for winter snow removal, probably yes, or they wouldn't move when you needed them the most. The lawn tractors like yours, probably no.


Engine oil analysis I totally get, but what would y'all expect an analysis to find in a sample of used hydraulic oil, other than water from condensation and possibly a very tiny amount of suspended solids that made it's way through the filters? The HST oil is not subjected to diesel combustion blow-by or extreme high temperatures and it's not lubricating an engines valve train.

Ran my last HST tractor over 4000 hrs. and maybe changed the trans hydraulic oil 3 times filter 5 or 6. Used the tractor nearly every day summer and winter sold it 2 years ago and it's still going strong. I'm not saying it was good practice just that I think every 300 hrs. is excessive.

Please don't take this wrong Billrog, but you live in the Okanagan valley and compared to eastern Ontario you live in the banana belt of Canada. The OP doesn't use his Kabota in winter, so he would not be seeing anywhere near the condensation accumulation that myself or anyone using their tractor for snow removal deal with every winter. Even less if it is stored in a heated garage over the winter months. If I want my tractor to function in the -20 to -30 degrees C that we see for 3 to 4 months of the year out here, it needs to have fresh hydraulic/transmission oil almost annually, once every 2 years at most ymmv. That's why my next house is going to have a heated garage

 

[rswyan]

... Engine oil analysis I totally get, but what would y'all expect an analysis to find in a sample of used hydraulic oil, other than water from condensation and possibly a very tiny amount of suspended solids that made it's way through the filters?

Similar stuff to what you would see in used engine oil analysis - primarily levels of wear metals, and additionally, the TAN (Total Acid Number) ... as well as any other contaminants (water, etc.)

Good idea to run a virgin (unused) sample of whatever hydraulic fluid you are running ... so that you have a baseline to compare an analyzed used sample to.

The HST oil is not subjected to diesel combustion blow-by or extreme high temperatures and it's not lubricating an engines valve train.

True ... but largely irrelevant.

 

[RickB]

Engine oil analysis I totally get, but what would y'all expect an analysis to find in a sample of used hydraulic oil, other than water from condensation and possibly a very tiny amount of suspended solids that made it's way through the filters? The HST oil is not subjected to diesel combustion blow-by or extreme high temperatures and it's not lubricating an engines valve train.

Any respectable oil analysis lab will want to know what component the sample came from, hours/miles of use, etc and brand and viscosity of the oil. The findings will include any contaminants related to wear, moisture, other contaminants or additive breakdown. The results will give a clear indication whether the oil should be changed out or retained, especially when sampling is ongoing and a baseline has been established.

If you truly believe that HST oils are not subjected to high temps you lack an understanding of that type of system. Improper operational methods can result in high oil temps and temperature related oil and component failure.

 

[Trials]

....
If you truly believe that HST oils are not subjected to high temps you lack an understanding of that type of system. Improper operational methods can result in high oil temps and temperature related oil and component failure.

Please feel free to comment on what I actually said.

 

[Trials]

...

True ... but largely irrelevant.

Have you ever seen transmission oil turn dark black like engine oil does?

 

[RickB]

Please feel free to comment on what I actually said.

I have. Actually I quoted you directly.

Review your post #8 in this thread where you claim HST oil is not subjected to extreme high temperatures.

 

[Trials]

...
If you truly believe that HST oils are not subjected to high temps you lack an understanding of that type of system. Improper operational methods can result in high oil temps and temperature related oil and component failure.

You missed the word extreme :/ Do you know what the combustion temperature of diesel fuel is, and do you know the maximum acceptable operating temperature of the oil in a hydraulic system?

 

[RickB]

You missed the word extreme :/ Do you know what the combustion temperature of diesel fuel is, and do you know the maximum acceptable operating temperature of the oil in a hydraulic system?

Most common tractor hydraulic oils exhibit heat stress when heated to between 185 and about 200 degrees F for extended periods. Most Hyd oil temp warning systems will activate in that range. Conventional wisdom wants to keep hydraulic oils no more than 100 degrees F above ambient.
I don't know offhand what the combustion temp of fuel oil is and frankly I don't care.

I have smelled cooked oil in hydrostatic transmissions and seen resulting damage to swash plates, slippers and pistons. Do you know the definition of extreme?

 

[RickB]

Have you ever seen transmission oil turn dark black like engine oil does?

Yes..

 

[Trials]

The two major pollutants of diesel combustion are carbon (that's the black stuff) and sulphur acids (that's the stuff that eats your engine up real quick and compels you to change your engine crankcase oil frequently) Neither of these chemical contaminants should be finding their way into your transmission in appreciable quantities or the associated hydraulic systems. If your hydraulic oil is turning black like your engine oil does and contains high volumes of sulphurous combustion residue, you have a serious problem.

 

[RickB]

The two major pollutants of diesel combustion are carbon (that's the black stuff) and sulphur acids (that's the stuff that eats your engine up real quick and compels you to change your engine crankcase oil frequently) Neither of these chemical contaminants should be finding their way into your transmission in appreciable quantities or the associated hydraulic systems. If your hydraulic oil is turning black like your engine oil does and contains high volumes of sulphurous combustion residue, you have a serious problem.

Your knowledge gap is widening. Everything you may know about internal combustion does not translate directly to what you think you know about hydrostatic transmissions.

Good day to you.

 

[Trials]

Good grief, you just don't get it do you :yo-yo:
Good day to you too.

 

[Billrog]

Trials every one is entitled to an opinion and I personally don't take offence to any comments contrary to mine. I expressed my opinion based on a tractor I owned from new since 1990 that kept 4k of mt. trails open all winter plowing snow & a 1/2 k of driveway. During the summer logging and brush hogging a min. of 20 acres. Not much of - 20 or 30 but -10 not uncommon and a wk here and there of - 20 to -30 on occasion.
The tractor was kept under cover ( just a roof ) but always plugged in with a timer to warm it up 4 hrs. before use. The engine oil & filter every 100 hrs. because the darn thing only held 3 lt. of oil.